When Cuban President Raul Castro named former engineering professor and long-time Communist Party insider Miguel Diaz-Canel as his first vice president and potential successor on Sunday, he chose managerial skills over flair. Diaz-Canel, 52, is the youngest non-military man to come so close to the pinnacle of power in Cuba since the Castro brothers took power in 1959. He was appointed first vice president on Sunday at a meeting of the National Assembly where Castro also announced he would step down in 2018 at the end of his second five-year term as president. Diaz-Canel would step into the presidency if...